Question

Why is a normal needed to define angle of incidence and angle of refration.PLEASE answer i will reward u 50 points

Answer 1

At the point of incidence  where the ray strikes the mirror, a line can be drawn perpendicular to the surface of the mirror. ... The angle between the incidence ray and the normal is known as the angle of incidence . The angle  between the reflected ray and the normal is known as the angle of reflection .

Answer 2

Answer:

Explanation:

The relation between the angle of incidence and the angle of refraction is known as Snell's Law. Since the light travels with different speed in different media, the direction of the ray of light will change when it crosses the boundary between the two media.